Electronic Telegram No. 5306 Central Bureau for Astronomical Telegrams Mailing address: Hoffman Lab 209; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org) URL http://www.cbat.eps.harvard.edu/index.html Prepared using the Tamkin Foundation Computer Network COMET P/2023 RL_75 = P/2002 T6 (NEAT-LINEAR) M. Rudenko, Minor Planet Center, reports that an apparently asteroidal object found by E. Schwab on CCD images obtained on Sept. 9 UT with the 0.8-m f/3 Schmidt telescope at Calar Alto (astrometry tabulated below), and given the minor-planet designation 2023 RL_75 by the MPC, has been identifed with comet P/2002 T6 (cf. IAUC 8002). 2023 UT R.A. (2000) Decl. Mag. Observer Sept. 9.09250 1 01 53.60 +10 40 13.5 21.7 Schwab 9.11089 1 01 53.27 +10 40 10.1 21.4 " 9.12929 1 01 52.96 +10 40 06.9 21.2 " The available astrometry appears on MPEC 2023-U279 and includes CCD astrometry (without comment) from Sept. 5.1-5.2 UT obtained by J. Maikner with a 0.30-m telescope (with the magnitude then given as 20.4-20.5). H. Sato (Bunkyo-ku, Tokyo, Japan) informs the Central Bureau that a post on an online discussion group suggesting the identification led him to observe the comet on Oct. 25.2, in which eleven stacked 120-s CCD exposures taken with a "Deep Sky Chile" 0.51-m f/6.8 astrograph at Rio Hurtado, Chile, shows a moderately condensed coma 4" in diameter with no tail; the magnitude was 19.3 as measured within a circular aperture of radius 2".2. The residuals for the recovery observations above are +0.12 deg in R.A. and +0.03 deg in Decl. from the prediction in NK 1066 and in the ICQ's 2021 Comet Handbook, with a corresponding correction of Delta(T) = -0.64 day. The following linked orbital elements by S. Nakano (Central Bureau) are from 431 observations spanning 2002-2023 (mean residual 0".7). Nakano states that the identification 2023 RL_75 = P/2002 T6 was made by Hidetaka Sato. The comet passed 1.67 AU from Saturn on 2018 Apr. 30 and will pass 1.67 AU from Jupiter on 2024 May 22 UT (coincidentally the same distances); also, the comet passed 1.59 AU from Jupiter in 1919 May and 0.89 AU from Saturn in 1924 Oct. Epoch = 2003 June 10.0 TT T = 2003 June 27.01545 TT Peri. = 217.57304 e = 0.5573311 Node = 209.04572 2000.0 q = 3.3870835 AU Incl. = 11.00925 a = 7.6515059 AU n = 0.04656758 P = 21.16 years Epoch = 2024 July 29.0 TT T = 2024 July 15.54787 TT Peri. = 218.95141 e = 0.5671066 Node = 205.99605 2000.0 q = 3.3895578 AU Incl. = 10.83576 a = 7.8300052 AU n = 0.04498430 P = 21.91 years Epoch = 2045 Oct. 27.0 TT T = 2045 Oct. 7.17193 TT Peri. = 218.14789 e = 0.5614668 Node = 205.57049 2000.0 q = 3.3764599 AU Incl. = 10.87077 a = 7.6994387 AU n = 0.04613340 P = 21.36 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 12.5 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2023 10 23 00 43.41 +07 11.4 2.893 3.858 163.6 4.2 19.5 2023 10 28 00 41.37 +06 45.1 2.902 3.842 158.1 5.5 19.5 2023 11 02 00 39.56 +06 20.0 2.918 3.826 152.5 6.9 19.5 2023 11 07 00 38.03 +05 56.5 2.941 3.811 147.0 8.1 19.5 2023 11 12 00 36.81 +05 35.0 2.970 3.796 141.6 9.3 19.5 2023 11 17 00 35.96 +05 15.9 3.004 3.781 136.3 10.4 19.5 2023 11 22 00 35.48 +04 59.4 3.043 3.766 131.0 11.4 19.5 2023 11 27 00 35.41 +04 45.7 3.087 3.752 125.9 12.3 19.5 2023 12 02 00 35.75 +04 35.0 3.135 3.737 120.8 13.1 19.6 2023 12 07 00 36.50 +04 27.2 3.186 3.723 115.9 13.8 19.6 2023 12 12 00 37.67 +04 22.5 3.240 3.709 111.0 14.3 19.6 2023 12 17 00 39.25 +04 20.7 3.297 3.696 106.3 14.8 19.6 2023 12 22 00 41.22 +04 21.9 3.355 3.682 101.7 15.2 19.7 2023 12 27 00 43.59 +04 26.0 3.415 3.669 97.1 15.4 19.7 2024 01 01 00 46.32 +04 32.7 3.475 3.656 92.7 15.6 19.7 2024 01 06 00 49.41 +04 42.0 3.536 3.644 88.4 15.7 19.7 2024 01 11 00 52.84 +04 53.7 3.597 3.631 84.2 15.6 19.8 2024 01 16 00 56.59 +05 07.6 3.658 3.619 80.0 15.5 19.8 2024 01 21 01 00.65 +05 23.7 3.718 3.607 76.0 15.3 19.8 2024 01 26 01 04.98 +05 41.6 3.776 3.596 72.0 15.1 19.8 2024 01 31 01 09.59 +06 01.2 3.834 3.584 68.1 14.8 19.9 2024 02 05 01 14.45 +06 22.4 3.889 3.573 64.3 14.4 19.9 2024 02 10 01 19.55 +06 45.0 3.943 3.563 60.5 14.0 19.9 2024 02 15 01 24.87 +07 08.8 3.995 3.552 56.8 13.5 19.9 2024 02 20 01 30.40 +07 33.6 4.044 3.542 53.2 12.9 19.9 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2023 CBAT 2023 October 30 (CBET 5306) Daniel W. E. Green